What rendering framework does blender use?
Blender, by default, uses its own rendering systems, depending on selection.


The offline renderer is a path tracing engine called Cycles.
The online renderer is a rasterization based engine called Eevee.
Both rendering engines harness CPU and GPU to different degrees, including the OpenGL, OpenCL, and CUDA based GPU libraries.


Blender used portions of Bullet for some physics calculations, with other approaches for its particle system interactions.